Suggest deref when coercing ty::Ref to ty::RawPtr
#71540
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r? @davidtwco (rust_highfive has picked a reviewer for you, use r? to override) |
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cc @oli-obk |
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r? @oli-obk |
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ldm0
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ty::Ref to ty::RawPtr
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I don't think we should permit it (at least not without an RFC). But you can use your logic to determine whether we could do it and then use a different error variant to signal that a suggestion should be generated to use a user-written deref. |
Thanks for reviewing! I'll work on it. Edit: Done! |
ldm0
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ty::Ref to ty::RawPtrty::Ref to ty::RawPtr
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The job Click to expand the log.I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact |
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Now it can even suggest |
oli-obk
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src/librustc_typeck/check/demand.rs
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| Some(steps).filter(|_| { | ||
| coerce | ||
| .unify( | ||
| coerce.tcx.mk_ptr(ty::TypeAndMut { | ||
| mutbl: hir::Mutability::Not, | ||
| ty: referent_ty, | ||
| }), | ||
| expected, | ||
| ) | ||
| .is_ok() | ||
| }) |
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This took me a moment to untangle. The filter is always executed, so I think it would be better formulated as
Suggested change
| Some(steps).filter(|_| { | |
| coerce | |
| .unify( | |
| coerce.tcx.mk_ptr(ty::TypeAndMut { | |
| mutbl: hir::Mutability::Not, | |
| ty: referent_ty, | |
| }), | |
| expected, | |
| ) | |
| .is_ok() | |
| }) | |
| coerce | |
| .unify( | |
| coerce.tcx.mk_ptr(ty::TypeAndMut { | |
| mutbl: hir::Mutability::Not, | |
| ty: referent_ty, | |
| }), | |
| expected, | |
| ) | |
| .ok().map(|_| steps) |
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Nice! I didn't expect to write like that.
oli-obk
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Apr 29, 2020
| ( | ||
| _, | ||
| &ty::RawPtr(TypeAndMut { ty: _, mutbl: hir::Mutability::Not }), | ||
| &ty::Ref(_, _, hir::Mutability::Not), |
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While I believe we could also do something for mutable references (both for staying in the same mutability and moving to const), this requires some care to get right without false positives, so maybe just leave a FIXME or open an issue?
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Yes, I missed the mutable references situation. I'll open another issue.
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This is great! just an impl nit then this lgtm |
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@bors r+ |
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📌 Commit a985879 has been approved by |
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Suggest deref when coercing `ty::Ref` to `ty::RawPtr` Fixes rust-lang#32122 Currently we do autoderef when casting `ty::Ref` ->`ty::Ref`, but we don't autoderef when casting `ty::Ref` -> `ty::RawPtr`. This PR make the compiler suggests deref when coercing `ty::Ref` to `ty::RawPtr`
bors
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Apr 30, 2020
Rollup of 5 pull requests Successful merges: - rust-lang#71205 (rustc: fix check_attr() for methods, closures and foreign functions) - rust-lang#71540 (Suggest deref when coercing `ty::Ref` to `ty::RawPtr`) - rust-lang#71655 (Miri: better document and fix dynamic const pattern soundness checks) - rust-lang#71672 (document missing stable counterparts of intrinsics) - rust-lang#71692 (Add clarification on std::cfg macro docs v. #[cfg] attribute) Failed merges: r? @ghost
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Thank you @ldm0 for getting around to this!! |
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May 2, 2020
Suggest deref when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability Fixes rust-lang#71676 1. Implement dereference suggestion when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability. 2. Extract the dereference steps into `deref_steps()`, which removes all the `use` and `pub` noise introduced by last PR rust-lang#71540, and makes the code more readable. 3. Use the `remove_prefix()` closure which makes the prefix removal more readable. 4. Introduce `Applicability` as a return value of `check_ref` to suggest `Applicability::Unspecified` suggestion. **Special**: I found it is not possible to genereate `Applicability::MachineApplicable` suggestion for situation like this: ```rust use std::ops::Deref; use std::ops::DerefMut; struct Bar(u8); struct Foo(Bar); struct Emm(Foo); impl Deref for Bar{ type Target = u8; fn deref(&self) -> &Self::Target { &self.0 } } impl Deref for Foo { type Target = Bar; fn deref(&self) -> &Self::Target { &self.0 } } impl Deref for Emm { type Target = Foo; fn deref(&self) -> &Self::Target { &self.0 } } impl DerefMut for Bar{ fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl DerefMut for Foo { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl DerefMut for Emm { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } fn main() { let a = Emm(Foo(Bar(0))); let _: *mut u8 = &a; //~ ERROR mismatched types } ``` We may suggest `&mut ***a` here, but the `a` is not declared as mutable variable. And also when processing HIR, it's not possible to check if `a` is declared as a mutable variable (currently we do borrow checking with MIR). So we cannot ensure that suggestion when coercing immutable reference to mutable pointer is always machine applicable. Therefore I added a `Applicability` return value in `check_ref()`. And move the `immutable reference -> mutable pointer` situation into a sperate test file without `run-rustfix`. (It seems that `run-rustfix` will also adopt `Applicability::Unspecified` suggestion, which is strange)
Dylan-DPC-zz
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May 3, 2020
Suggest deref when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability Fixes rust-lang#71676 1. Implement dereference suggestion when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability. 2. Extract the dereference steps into `deref_steps()`, which removes all the `use` and `pub` noise introduced by last PR rust-lang#71540, and makes the code more readable. 3. Use the `remove_prefix()` closure which makes the prefix removal more readable. 4. Introduce `Applicability` as a return value of `check_ref` to suggest `Applicability::Unspecified` suggestion. **Special**: I found it is not possible to genereate `Applicability::MachineApplicable` suggestion for situation like this: ```rust use std::ops::Deref; use std::ops::DerefMut; struct Bar(u8); struct Foo(Bar); struct Emm(Foo); impl Deref for Bar{ type Target = u8; fn deref(&self) -> &Self::Target { &self.0 } } impl Deref for Foo { type Target = Bar; fn deref(&self) -> &Self::Target { &self.0 } } impl Deref for Emm { type Target = Foo; fn deref(&self) -> &Self::Target { &self.0 } } impl DerefMut for Bar{ fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl DerefMut for Foo { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl DerefMut for Emm { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } fn main() { let a = Emm(Foo(Bar(0))); let _: *mut u8 = &a; //~ ERROR mismatched types } ``` We may suggest `&mut ***a` here, but the `a` is not declared as mutable variable. And also when processing HIR, it's not possible to check if `a` is declared as a mutable variable (currently we do borrow checking with MIR). So we cannot ensure that suggestion when coercing immutable reference to mutable pointer is always machine applicable. Therefore I added a `Applicability` return value in `check_ref()`. And move the `immutable reference -> mutable pointer` situation into a sperate test file without `run-rustfix`. (It seems that `run-rustfix` will also adopt `Applicability::Unspecified` suggestion, which is strange)
Dylan-DPC-zz
pushed a commit
to Dylan-DPC-zz/rust
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May 3, 2020
Suggest deref when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability Fixes rust-lang#71676 1. Implement dereference suggestion when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability. 2. Extract the dereference steps into `deref_steps()`, which removes all the `use` and `pub` noise introduced by last PR rust-lang#71540, and makes the code more readable. 3. Use the `remove_prefix()` closure which makes the prefix removal more readable. 4. Introduce `Applicability` as a return value of `check_ref` to suggest `Applicability::Unspecified` suggestion. **Special**: I found it is not possible to genereate `Applicability::MachineApplicable` suggestion for situation like this: ```rust use std::ops::Deref; use std::ops::DerefMut; struct Bar(u8); struct Foo(Bar); struct Emm(Foo); impl Deref for Bar{ type Target = u8; fn deref(&self) -> &Self::Target { &self.0 } } impl Deref for Foo { type Target = Bar; fn deref(&self) -> &Self::Target { &self.0 } } impl Deref for Emm { type Target = Foo; fn deref(&self) -> &Self::Target { &self.0 } } impl DerefMut for Bar{ fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl DerefMut for Foo { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl DerefMut for Emm { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } fn main() { let a = Emm(Foo(Bar(0))); let _: *mut u8 = &a; //~ ERROR mismatched types } ``` We may suggest `&mut ***a` here, but the `a` is not declared as mutable variable. And also when processing HIR, it's not possible to check if `a` is declared as a mutable variable (currently we do borrow checking with MIR). So we cannot ensure that suggestion when coercing immutable reference to mutable pointer is always machine applicable. Therefore I added a `Applicability` return value in `check_ref()`. And move the `immutable reference -> mutable pointer` situation into a sperate test file without `run-rustfix`. (It seems that `run-rustfix` will also adopt `Applicability::Unspecified` suggestion, which is strange)
Dylan-DPC-zz
pushed a commit
to Dylan-DPC-zz/rust
that referenced
this pull request
May 3, 2020
Suggest deref when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability Fixes rust-lang#71676 1. Implement dereference suggestion when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability. 2. Extract the dereference steps into `deref_steps()`, which removes all the `use` and `pub` noise introduced by last PR rust-lang#71540, and makes the code more readable. 3. Use the `remove_prefix()` closure which makes the prefix removal more readable. 4. Introduce `Applicability` as a return value of `check_ref` to suggest `Applicability::Unspecified` suggestion. **Special**: I found it is not possible to genereate `Applicability::MachineApplicable` suggestion for situation like this: ```rust use std::ops::Deref; use std::ops::DerefMut; struct Bar(u8); struct Foo(Bar); struct Emm(Foo); impl Deref for Bar{ type Target = u8; fn deref(&self) -> &Self::Target { &self.0 } } impl Deref for Foo { type Target = Bar; fn deref(&self) -> &Self::Target { &self.0 } } impl Deref for Emm { type Target = Foo; fn deref(&self) -> &Self::Target { &self.0 } } impl DerefMut for Bar{ fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl DerefMut for Foo { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl DerefMut for Emm { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } fn main() { let a = Emm(Foo(Bar(0))); let _: *mut u8 = &a; //~ ERROR mismatched types } ``` We may suggest `&mut ***a` here, but the `a` is not declared as mutable variable. And also when processing HIR, it's not possible to check if `a` is declared as a mutable variable (currently we do borrow checking with MIR). So we cannot ensure that suggestion when coercing immutable reference to mutable pointer is always machine applicable. Therefore I added a `Applicability` return value in `check_ref()`. And move the `immutable reference -> mutable pointer` situation into a sperate test file without `run-rustfix`. (It seems that `run-rustfix` will also adopt `Applicability::Unspecified` suggestion, which is strange)
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Fixes #32122
Currently we do autoderef when casting
ty::Ref->ty::Ref, but we don't autoderef when castingty::Ref->ty::RawPtr. This PR make the compiler suggests deref when coercingty::Reftoty::RawPtr